When Bob Dylan plugged in for the first time at the Newport Folk Festival, Bob Gruen was there. When the Sex Pistols signed their landmark recording contract with EMI, he was there, too. And when Elton John made his stateside debut as the opening act for Leon Russell, Gruen eyed it through his lens.

As a rock photographer, Gruen has witnessed a number of key moments in rock history. His website (bobgruen.com) features pages upon pages of photos he has taken of icons such as Aerosmith, Black Sabbath, Eric Clapton, Elvis Presley, and the Who. Gruen, who has published two books of his photos of John Lennon, will be at the Rock and Roll Hall of Fame on March 29 to present a "slide talk" featuring over 100 of his photos of Lennon, whom he knew for nine years.

Though he has documented some of rock's most important moments, Gruen isn't about to wax philosophical about what any of those events might have meant; he prefers to think of himself as a guy with a camera who likes to party with the stars.

"I don't try to put things in perspective," Gruen says via phone from his home in New York. "I look ahead and just keep doing it. Looking back, it does seem that something happened in the world of rock and roll in the late '60s and all through the '70s that affected not just the way people dance, but the way they think and how they get together and relate to things. To me, I didn't really seek it out as much as I was a part of it. I thought it was better than working in an office."

Gruen grew up on Long Island and was introduced to photography by his mother at an early age. By the time he was 11, he was photographing schoolmates in summer-camp plays. When he turned 18, he moved to Greenwich Village and lived with musicians. After he shot the Newport Folk Festival in 1965, his work began earning him admirers in high places. Among the artists he photographed were Ike and Tina Turner, the Bee Gees, and Tommy James & the Shondells. He met Lennon and his wife, Yoko Ono, through a writer friend who was doing a story on the former Beatle. Like other artists, Lennon became enamored of Gruen's work and called on him regularly. Gruen's chronicling of Lennon blossomed into a friendship, as the photographer recalls it. That Gruen was Lennon's friend and not just another photographer is a point heavily emphasized in Listen to These Pictures: Photographs of John Lennon, a Gruen book published in 1985 that is now out of print.

"Because we were friends, there was a relaxed intimacy, and he wasn't posing," Gruen says. "I had the freedom to take photos all the time and just stop by and drop in, even more than most friends. I just had a kind of access.

"As I realized that more and more people were turned away, and I could come in at two in the morning, it started to be a responsibility, that I had to go."

The photos in Listen to These Pictures are indeed candid. Highlights include images of Lennon and Ono working with Mick Jagger in the studio and Gruen's iconic shot of Lennon making the peace sign in front of the Statue of Liberty. But one can't help but think that there's a side to Lennon that's not exposed here. After all, in the narrative that accompanies the photos, Gruen recounts one night when Lennon was so upset that he started cursing, using words that Gruen says he "never heard before or since." And Lennon's relationship with Ono in New York -- at the time they were holed up at the Dakota Hotel -- has often been described by Lennon biographers as one of the most difficult periods of his life. Yet Gruen, who says he "tends not to read" most of the material written about Lennon because it's "generally not true," maintains that Lennon was content up until the time of his death in 1980.

"Most of the time, when I saw him, he was pretty happy," he says. "There are some people who said that he should go out drinking with the boys, and that 'that woman' was keeping him home. But when he was out drinking with the boys, he wasn't really happy about it. When I saw him when Sean was born, it was one of the happiest days of his life."

Perhaps most indicative of Gruen's approach to photographing the stars is the section of his website titled "photos of Bob with famous folks." There, Gruen can be seen mugging with artists such as Kiss, Iggy Pop, Deborah Harry, and the Sex Pistols. It's enough to suggest that there's a fine line separating Gruen from fanatics who go backstage with disposable cameras. Gruen admits his goal is to "flatter" his subjects, and he even allows artists to pick and choose the photos he uses for exhibits and publication.

"I know a few colleagues who make a point of trying to embarrass people," Gruen says. "One woman told me her idea was to show something about someone's personality that's not usually seen, something they try to keep hidden. I told her I do the opposite: I like people to look at my pictures and say that that's exactly the way they feel about themselves. I think one of my favorite compliments that I've gotten from all kinds of people is when they ask me for an extra photo to send to their mother."